Transmission of pictures



Jan. 24, 1928.

J. F. NIELSEN TRANSMISSION OF, PICTURES Filed July 24. 1924 [IIIIIIHIIIIIIYIIIIITHIII'IlLLl fimmmmmmuummmu Patented Jan. 24, 1928.

UNITED STATES PATENT OFFICE.

JOHN F. NIELSEN, OF LONG- ISLAND CITY, NEW YORK, ASSIGNOR TO WESTERN ELEC- TRIC COMPANY, INCORPORATED, 015 NEW YORK, N. Y., .A. CORPORATION OF NEW YORK.

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Application filed July 24, 1924. Serial No. 727,855.

This invention relates to telegraph systems, and more particularly, to the transmission of pictures telegraphically.

It is the object of the invention to effect the reproduction of pictures in a facile and expeditious manner through the use of simple, eflicient, reliable and comparatively inexpensive apparatus.

In accordance with the above object the present invention provides for the transmission of code combinations of signaling impulses representing the various elemental tone values of the picture to be transmitted and its reproduction at a remote station by selectively operated apparatus responsive to the various code combinations of impulses to control the exposure of a photo sensitive surface.

A better understanding of the invention may be had from the following description, taken in conjunction with the accompanying drawing which illustrates one embodiment of the invention and in-which Fig. 1 shows schematically the apparatus and circuits employed for the reproduction of a picture transmitted electrically. Fig. 2 illustrates a modified form of the light controlling device shown in Fig. 1; while Fig. 3 shows a section of a tape which has previously been perforated to represent the various code combinations of impulses in accordance with the different elemental tone values of the picture to be transmitted.

Referring now to Fig. 1 a line conductor 5 is shown extending from station A to station B, station A being equipped for the transmission of code combinations of signaling impulses representing the different elemental tone values of the picture to be transmitted, while at station B apparatus is located for reproducing the picture in accordance with the various code combinations of signaling impulses. At the transmitting station A a synchronous multiplex distributor 8 comprising a continuous ring 9. a segmented ring 10 and a brusharm 11 is provided. Connected to the segments constituting one channel of the multiplex distributor 8 are the operating elements of a tape transmitter 7 which is adapted to receive a perforated tape such as shown in Fig. 3. Inasmuch as this mechanism is similar to that employed in printing telegraph systems and is well known, a detailed description thereof is believed unnecessary.

number of well-known mechanisms.

.well as segments 20, 21 and 22. The respective segments are arranged to be bridged by brushes carried by a brush arm 23. The

segments of the distributor 17 corresponding to the segments of distributor 8 allotted to transmitter 7 are connected to selecting magnets25, 26, 27, 28 and 29. These selecting magnets form a part of a selectively operated apparatus for controlling predetermined circuits. Similar apparatus is employed in connection with printing telegraph receivers and comprises a plurality of selecting elements 30, 31, 32, 33 and 34, each of these elements being individual to one of the selecting magnets. Upon the energization of the selecting magnets, the selecting elements 30 to 34 will be positioned in various combinations for selecting one of a plurality of notched bars, such as 37, 38 and 39, there being twenty-six of these bars, but for simplicitys sake only three have been shown. These bars control the closure of circuits extending to the segments of a segmented distributor 42. The segments of the distributor 42 are arranged to be connected with a continuous ring thereof by means of a brush carried by a continuously rotating brush arm 43. The brush arm 43 which bears a definite phase relation to brush arm 23 is mounted on a shaft 44 to which there is also secured a disc 49 of density graduated from substantial transparency to comparative opacity. The continuous ring of the distributor 42 is connected to an electromagnet 45 having associated with its armature a shutter 46 serving to shield the light source 48 from the disc 49 and the sensitized film 50.

The sensitized film 50 is mounted on a drum 51 which is secured to a shaft 52. As is the practice in printing telegraph receivin mechanisms the drum 51 is capable of being advanced step-by-step to bring difierent areas of the film in line with the rays of light transmitted from the light source 48 as well as being arranged to be rotated and returned to its normal or extreme right-hand position.

The mechanism for accomplishing the above features comprises a cylindrical ratchet which is secured to the shaft 52 by a key 56, and operatively associated with the ratchet 55 is a magnet 57 having associated therewith a stepping pawl which upon each energization of the electromagnet engages the next succeeding tooth in the ratchet 55 and causes it to advance one step under the tension of a spring 58. In order to hold the drum 51 in its advanced position, a holding pawl under the control of an electromagnet 59 is provided. Mounted on the shaft 52 is a ratchet wheel 60 which has operatively .associated therewith a pawl operated by an electromagnet 62 and which functions upon the operation of the magnet 62 to rotate the drum 51. The energization of the magnets 59 and 62 is controlled through the actuation of contacts 64 and 65 respectively. Each of these contacts is operated upon the selection of the code or notched bar individual thereto. These bars are designated by the numerals 67 and 68 and are adapted to be selected upon the movement of the selecting elements 30 to 34 so that they are allowed to more to the right sufiiciently to close the associated contacts. The energization of advancing magnet 57 is effected automatically upon the deenergization of relay 66.

The operation of the system is as follows: Suppose first, however, that the picture to be transmitted has been scanned and a tape perforated in accordance with the differentelemental tone values of the picture. A mech anism suitable for perforating the tape is shown in Patent No. 1,580,896, granted to H. E. Ives April 13, 1926. The tape having been perforated in accordance with the different elemental tone values or densities of the picture, is passed through the transmitter 7. Upon the alignment of the perforations in the tape 6 with the operating elements of the transmitter 7 the current sources associated therewith will be connected to the respective segments forming a part of the outer ring 10 of the distributor 8. As the brush arm 11 of the distributor 8 rotates the segments will be bridged with the continuous ring 9 and code combinations of impulses transmitted to station B over the line 5. a

The impulses impressed on the line 5 due to the setting of the operating elements of the transmitter 7 effect the operation of the receiving relay 15 and inasmuch as the distributor 17 rotates in synchronism with the distributor 8, the segments corresponding to the segments of the distributor 8 at the transmitting station A will be connected with the continuous ring 16 which results in the energization of the selecting magnets 25 to 29 depending upon the position of the armature of the receiving relay 15 at the time the brush is passing over the respective segments.

For the case selected as a matter of illustration, assume that the selecting magnets 25 to 29 are energized so as to select notched bar 37. It should be noted, however, that the movement of the code bar 37 is not effected simultaneously with the movement of the selecting elements 30 to 34, but occurs following the energization of magnet 35. This magnet 35 is controlled through segment 20 of the distributor 17 and functions to release the mechanism through the instrumentality of which the bars 37, 38, 89 and others are operated. For the details of such a mechanism reference should be made to U. S. Patcut to H. Pfannenstiehl No. 1,540,170'granted June 2, 1925.

Because of the selection of the bar 37 the contacts associated therewith are closed. These contacts are connected to segment 69 of the distributor 42. Now upon the rota tion of the brush arm 43 which as previously stated is continuous, the segment 69 will be bridged with the continuous ring, whereupon the electromagnet 45 will be energized.

In order that electromagnet 45 will be energized at the proper instant, it is necessary that the brush arm 48 bear a definite phase relation with respect to brush arm 23. Preferably, the brush arm 43 rotates at twice the speed of brush arm 23. Such an arrangement insures the completion of any circuits which may have been conditioned through the operation of the selecting mechanism, irrespective ot the position of the brush arm 43 at the instant the particular notched bar was selected. Also, to guard against possible false exposures. the source of operating current for electromagnet 45 is placed under the control of relay 66, which has two windings and which is arranged to be energized upon the passage of brush arm 23 on to segment 21, and later deenergized by the same brush engaging segment 22. Since the segment 22 is located substantially 180 from segment 21 and since the brush arm 43 r0- tates twice .as fast as brush arm 23, it is therefore insured that the electromagnet 45 will be energized at the proper time, thereby resulting in the exposure ofthe film 50 for each selection.

The shutter 46 will be removed from the path of the light rays from the source 48 and since the particular density gradation of the disc 49 corresponding to the segment 69 is in line with the light rays, the film 50 will be exposed in accordance with the light transmission characteristics of this parwidth. Thus, when it is positioned in the i path of thelight rays from the light source 48, the film will be exposed in accordance with the amount of light passed through the particular slot or aperture.

Following the exposure of the film, the stepping mechanism 57 is operated for advancing the drum 51 and in turntbringing an unexposed area of the film 50 in line with the rays from the light source 48,

When the end of the particular line ex posure has been reached, thejmechanism is operated such that the code bar 67 is selected for energizing electromagnet 59. and withdrawing the holding pawl associated therewith. The withdrawal of the holding pawl of the magnet 59 permits the spring 58 to. act

to restore the drum 51 to its extreme right-,

hand position.

Also when it is desired to bring the next succeedin path of t e light rays, the electroniagnet 62 is operated through the closure of contacts 65. This operation is similar to that described in connection with the operation and selection of bar 67.

It is obvious that various modifications and changes may be made without departing from the spirit and scope of theinvention. It is intended therefore, that the invention should not be limited by the particular structure and circuits shown but only by theappended claims.

The invention claimed is: 1. A system for reproducing pictures transmitted electrically, comprising means line of the film in line with the for producing combinations of signaling impulses representing the various elemental tone values of the picture, a selecting mechanism operated in accordance with said combinations of signaling impulses, a current path conditioned upon the operation of said selecting mechanism, a rotating distributor having a plurality of segments, a disc provided with different density gradations, the number of gradations being'equal to the different elemental tone values of the picture, said disc being adapted to be rotated in a particular phase relation with regard to said distributor, a light source, means operated upon'the completion of said current ath by said distributor, and a sensitized fi m illuminated by said light source in accordance with the portion of said disc then located in said light path, when said last mentioned means is operated.

2. In a system for reproducing pictures transmitted electrically, means for producing combinations of signaling impulses representing the difi'erent elemental tone. values of a picture, an element with a light sensitive surface, a selecting mechanism operated in accordance with said combinations of signaling impulses, said selecting mechanism comprising a plurality of selectable elements, means for operatin said elements in various combinations, anot er plurality of selectable elements, one of said other elements being selected upon the positioning of the first mentioned elements, a current path controlled by each of said other elements, a disc provided with different density gradations from substantial transparency to opacity, a light shutter, and means cooperating wlth said disc for completing the current path conditioned by one of said other selectable elements at the instant when the disc is in its'proper position for operating said shutter to illuminate said sensitive surface in accordance with a particular elemental tone i 

